Elastic-fluid ejector



July 1, 1924. 1,499,350

A. DELAS ELASTIC FLUID EJECTOR Original Filed July 13, 1920 2 Sneaks-Shee Pressure qtrhe sucfionside 0F Hue Firs1"S+aqe.

INVENTOR ZZZ/q,

Patented July 1, 1924.

more!) STATES PATENT OFFICE.

CONDENSER CORPORATION,

DELAWARE.

ELASTICJLUID ECTOR.

Application filed July 13, 1920, Serial No. 396,018. Renewed November 15, 1923.

7'0 all whom it may concern: I

Be it known that I, ALBERT DELAS, a citizen of France, residing atParis, France, have invented certain new and useful Improvements in Elastic-Fluid Ejectors, of which the following is a full, clear, and exact description.

This invention relates to ejectors capable of receiving a gaseous fluid and raising the pressure of the same. More specifically it relates to ejectors adapted to produce a high degree of vacuum in a chamber such as a main condenser of a steam actuated prime mover.

In my copending applications, Serial Nos. 260,600%, 260,601% and 324,391, of which this application is a continuation, in part, I have disclosed, in its various stages of development by me, a steam ejector comprising a diffuser having a substantially cylindrical outlet and in which cooling fluid is circu lated around and in contact with the exterior of all portions of said diffuser. Among other advantages pointed out in my prior applications it may be stated that the stability of such an ejector is greatly increased, its efficiency is enhanced and higher degrees of vacuum may be consistently maintained than was possible with the prior art devices.

In addition to the advantages enumerated above in my prior applications I wish to point out an additional and practically important feature inherent in my invention and not possessed by the prior art devices. When comparatively high degrees of vacuum are desired, it has been proposed to employ a multi-stage ejector system. Such a system may comprise a first stage e ector, which discharges directly, or indirectly, through an intermediate condenser, into the suction-inlet of a s 0nd stage ejector. I have discovered that f the diffuser of each stage is provided with a substantially cylindrical outlet portion (instead of a diverging outlet) and cooling means are provided for the diffusers there is a substantially constant relationship between the ratio of compression of the first stage to that of the second stage, even though the total ratio of compression varies. In other words:

ratio of compression of the 1st stage k ratio of compression of the 2nd stagewhere k is 'a constant although the pressure system (with intermediate condenser at the intake side of the first stage varies over a comparatively wide range. This difference between a two stage system embodying my invention and a system employing convergent-divergent diffusers may be clearly grasped by inspection of the curves in Fig. 3 which curves were determined as the result of actual tests and the co-ordinates are as indicated. Curve A was obtained from readings taken during the operation of a two stage system employing an intermediate or inter-stage condenser and in which the diffusers of the ejectors were of the convergent-divergent type. It will be seen that the ratio of the ratios ofcompression varies on variation of the pressure at the suction side of the first stage. Curve B is a corresponding curve but plotted from reading taken during the operation of a two stage embodymg my invention as illustrated in Fig. 1. It will vbe noted that the ratio of ratios of compression is practically constant for variations from o to d of the pressure at the I suction side of the first stage. It Will be noted that I have omitted reference to actual numerical values because these will de pend on the design and conditions of operation of the particular apparatus. The curves A, however, show the relationship of the various factors which is sufficient for the present purpose. It may be stated, however, that the pressure variation represented by the horizontal distance 0-d is substantially equal to or greater than that permissible in practise in main condensers of steam power plants.

The importance of this novel feature will be appreciated when it is borne in mind that a two stage system comprising an interstage or intermediate condenser operates most efliciently with a predetermined ratio of ratios of compression. To state this in. another way, such a system will operate with a minimum steam consumption at a certain ratio of ratios of compression. If the ratio of ratios of compression is either increased or decreased the total steam consumption will rise.

It is also true that even though there is no intermediate condenser employed in a two stage system embodying my invention, nevertheless the ratio of ratios of compression of the two stages is substantially constant within the limits of permissible variation of pressure in the main condenser being evacuated. Furthermore 1n multi-stage ejector systems which employ no intermediate condenser it is found that a certain ratio of ratios of compression of the two stages leads to greater economy than other ratios.

' It may therefore be stated tha one of the principal objects of the present in ention is to provide a plural stage ejector system designed for a predetermined ratio of ratios of compression and provided with means for maintaining this ratio of ratios constant for a considerable variation in pressure at the suction side of the first stage. Other objects and advantages will appear as my invention is hereinafter disclosed.

Referring to the drawings which illustrate what I now consider preferred forms of my invention,

Fig. 1 is a sectional elevation of a two stage apparatus in which an intermediate condenser is employed.

Fig. 2 is a diagram employed in explaining my invention.

Referring to Fig. 1 the chamber 1 is adapted to be supplied with steam or other motive fluid under pressure the opening 3 being plugged when the device is in operation.

The steam from said chamber passes through an expanding nozzle 4 into the mixing chamber 5 which communicates at 6 with the source of fluid to'be exhausted as for example the air and vapor outlet of a main condenser (not shown). A diffuser 7 communicates at its inlet end with said chamber 5 and is preferably constructed in the form ofa thin-wall metallic tube of good heat conductivity. It will be noted that while the tube 7 is converging at its upper portion, it is cylindrical atits neck and outlet portions. The second stage ejector comprises elements 1 to 7 so 7 similar to elements 1 to 7 that no specific description of the former need be furnished. A common casing is provided for the two ejectors, said casing being made up. of a plurality of sections suitably secured together. One section 8 comprises the chambers 5 and 5','already described, and is surmounted by and has secured thereto the steam chambers 1 and 1'. The section 9 is provided with two chambers 10 and 10 through which the respective difl'users 7, 7 extend and which chambers are connected by a passage 11. Be-

'tween said chambers 10 and 10 but not in direct communication therewith is a passage 12 provided with an inlet 14 and an outlet 13 which registers with the air and va or inlet 6 of the mixing chamber 5". e diffuser 7 is flanged outwardly at its upper end and the flange so formed seats between a shoulder 15 and a ring 16 screw threaded into the casing. The lower end of the;

diffuser 7 is connected to the casing by means of a liquid tight expansion joint co structed shown) substantially as follows: A flanged externally threaded annular member 17 is soldered, brazed or otherwise secured to the lower end of the difiuser 7. A resilient or spring washer 18 is gripped at its inner pcriphery between the flange of the member 17 and a nut 19 screwed thereon. The outer periphery of the washer 18 seats against the shoulder 20 of the casing and is firmly pressed thereagainst by the externally threaded ring 21 screwed into said casing. By virtue of the construction above described the diifuser 7 may expand quite freely in a longitudinal direction with respect to the casing but liquid in chamber 10 cannot enter the diffuser 7 nor leave the said chamber except through the passage 11. The chamber 10 is provided at its upper portion with an inlet 22 adapted to receive cooling water or liquid from any suitable source such as the circulating loop of the main condenser (not This cooling water may be sea water and enters the chamber 10 at 22, flows around the difi'user 7 and leaves at 11. In order to insure a rapid circulation past the diffuser a sleeve 23 is mounted around and in comparatively close proximity to the diffuser 7, the upper portion of said sleeve terminating in a cylindrical portion 24 which surrounds the converging portion of the diffuser tube 7. The sleeve 23 is'held in position between a shoulder 26 and the ring 16 already described. A plurality of inlet openings 25 are provided adjacent the upper end of sleeve 23. Recapitulating, the cooling liquid enters at 22, enters the sleeve 23 at 25,

flows down in the latter around diiiuser 7 at a rapid rate due to the small cross-section, flows up in chamber 10 on the exterior of sleeve 23 and out at 11.

The elements 16, 23, 2 1' and 25' of the second stage ejector correspond to the elements 16, 23, 24 and 25 of the first stage. It will be noted, however, that the sleeve 23' extends upwardly into its cylindrical portion 24 for a substantial distance. The expansion point 17',-18'19'21' of the second stage diffuser 7 corresponds generally to the joint 17 181921 of the first stage diffuser 7. The nut 19' is, however, shown slidably engaging the inner wall of the ring 21. The cooling liquid passing through the passage 11 enters through the openings 25 flows rapidly down between the exterior of tube 7 and the interior of sleeve 23 into the chamber 10 and leaves at 27, whence it flows to a waste or other suitable outlet;

The casing section 28 is provided with a chamber 29 formed by a wall or partition 30 through which a sleeve 31 extends, said sleeve being screw threaded into said wall. The lower end of the diffuser 7 extends into the upper end of the sleeve 31, suflicient clearance being provided as not to interfere with the expansion and contraction of said diffuser. The sleeve 32 is pierced by holes 32 so that cool, fresh (or Sweet) water,

entering the chamber 29 at 33 from anysuitable source, flows through said holes and condenses the steam leaving the first stage. The uncondensed vapor and gas leaving the sleeve 31 passes through the passage 34:, through opening 35, which registers with opening 14, upwardly through passage 12, openings 13 and 6 into the mixing chamber 5 of the second stage. The condensing water leaves the inter-stage condenser 29-31, together with the water of condensation, at the lower end of the sleeve 31 and passes out through the opening 37. The casing section 28 is also provided with a passage 36 through which the mixture of steam and gas leaving the second stage passes. The passage 37 is shown provided with an extension 38 which may be connected through a U-bend to the main condenser (not shown). Bearing in mind that the inter-stage pressure is higher than the pressure at the suction side of the first stage it will be clear that the condensing water and-the water of condensation will readily flow from. the extension 38. The passage 36 is provided with an extension 39 which may discharge to atmosphere but preferably discharges into the hot well which supplies the boilers.-

The operation of the form of invention shown in Fig. 1 may be briefly summarized as follows. The air or air and vapor whose pressure is to be raised enters the mixing chamber 5 at 6 and is entrained by the steam or motive fluid entering the nozzle 4. The resulting mixture enters the diffuser tube 7 where its pressure is raised by conversion of velocity into pressure. The mixture of entrained and motive fluids enters the intermediate condenser where a large portion, if not all, of the steam is condensed. The uncondensed vapor and gas pass upwardly through the passages 34, 12 and 6 and enter the mixing chamber 5 of the second stage where it is entrained by steam or motive fluid entering through the nozzle 4. The pressure is elevated in the diffuser 7' by conversion of velocity into pressure and mixture of gas and vapor leaves at 39. By virtue of the means for cooling the diffusers 7 and 7 important results are achieved. Some of these results are enumerated in my prior applications and need not be repeated here. To the advantages set forth in the said prior applications should be added the additional advantage herein set forth, i. e., for a considerable variation in total ratio of compression the ratio of the ratios of compression of the two stages is substantially constant.

As hereinbefore explained multi-stage ejector systems. embodying my invention &

maintain the ratio of the ratios of compression substantially constant for a considerable variation in pressure at the suction side or" the first stage. To emphasize this result I wish to explain the property in still another way. The ratio (-R) of the ratios of compression of a two stage system is given by the following equation R is substantially constant for variations of the latter between the limits 0 to d (Fig.

Therefore,

where k is a constant. Transposing:

where K is a constant and equal to the quotient of 7c and 7a. In other Words the inter-stage suction pressure, in a two stage system embodying my invention, tional to the square root of the pressure at the suction side of the first stage for all variations of the last mentioned pressure between the limits permitted in practice in main condensers of steam power plants.

lV hat I claim is:

1. In combination in an ejecting apparatus, an ejector comprising a combined combining and diffuser tube having an inlet to which fluid to be ejected is delivered, and a nozzle for delivering motive fluid to said tube, a second ejector arranged to communi- Cate with the source of fluid to be ejected and to discharge both the fluid ejected and the motive fluid delivered to it to the inlet of the first mentioned ejector, an interstage condenser into which said second ejector dis charges and means for maintaining the ratio of the ratios of compression of said ejectors substantially constant over a considerable variation in the total ratio of compression of said apparatus.

2. An ejecting system comprising in combination, a plurality of ejectors operating in series, the first of said ejectors including a diffuser, a mixing chamber communicating with the inlet end of said diffuser, and a motive fluid supply nozzle projecting into said is propordiffuser, an interstage condenser interposed between said difl'users and means for maintaining the ratio of the ratios of compression of the first stage and second stage ejectors substantially constant over a considerable variation in the total ratio of compression of the system.

3. An ejecting system comprising in combination, a plurality of ejectors operating in series, the first of said ejectors includin a diffuser having a substantially cylindrical outlet portion, a mixing chamber communicating with the inlet end of said difi'user, and a motive fluid supply nozzle projecting into said mixing chamber, the second ejector of the series comprising a difl'user having a substantially cylindrical outlet portion and communicating at its inlet end with the discharge end of the first mentioned diffuser, and a nozzle for delivering motive fluid to the second named difl'user, a condenser interposed between said di sers and means for cooling the outlet portion of each ofsaid diffusers:

4. In combination in an ejecting apparatus, a plurality of steam actuated ejectors connected to operate in series on the fluid to be ejected, a condenser interposed between said diffusers and means for maintaining the ratio of the ratios of compression of said ejectors substantially constant over a considerable variation in the total ratio of compression of said apparatus.

5. In combination in an ejectin apparatus, a plurality of steam actuate ejectors connected to operate in series on the fluid to be ejected and each including a diffuser having a'substantially cylindrical-outlet portion, a condenser interposed between said diffusers and means for cooling the outlet portion of each of said difi'users.

6-. In combination, a steam actuated ejector comprising a difl'user having a substantially cylindrical outlet, an inter-stage condenser into which said diffuser discharges, 'a second steam actuated ejector comprising a difl'uscr having a substantially cylindrical outlet portion and communicating at its inlet end with said condenser, and means for cooling the outlet portion ofeach of said difl'users. I

7. In combination, an inlet chamber, a

nozzle through which motive fluid may be directed into said chamber, a casing having a coolmg chamber and a condensing chamher, a difliuser communicating with said inlet chamber and extending through said cooling chamber, a perforated sleeve forming a continuation of said diifuser and extending through said condensing chamber, and an expansion joint connecting said diffuser and casing.

8. In combination, an inlet chamber, a nozzle through which motive fluid may be directed into said chamber, a cooling chamber, a condensing chamber, and a diffuser connecting said inlet and condensing chamlfiers and passing through said cooling cham- 9. In combination, an inlet chamber, a nozzle through which the motive fluid may be directed into said chamber, a' cooling chamber, a condensing chamber, a difluser connecting said inlet and condensing chambers and passing through said cooling chamber, and means for preventing interchange of liquids between said cooling and condensing chambers.

10. In combination, an inlet chamber, a nozzle through which motive fluid may be directed into said chamber, a cooling chamber, a condensing chamber, a difl'user connecting said inlet and condensing chambers and passing through said cooling chamber, and means including a flexible connection between the inner wall of said cooling chamber and said difluser for preventing interchange of liquids between said cooling and condensing chambers.

11.- In a multi-stage ejector, a common casing for the ejectors composed of a plurality of sections secured to each other, one

of said sections comprising the mixing chambers, a second section comprising the diffuser chambers, and a third section comprising the chambers into which the fluid from the difl'users is discharged.

12.- In a multi-stage ejector, a common casing for the ejectors composed of a plurality of sections secured to each other, one of said sections comprising the mixing chambers, a second section comprising the difluser chambers, and a third section comprising the chambers into which the fluid from the difl'users is discharged, said sections being provided with means for establishing communication between said diffusers for the fluid being ejected and also provided with intercommunicating means for the circulation of a cooling fluid for said diffusers.

In testimony whereof I hereunto afiix my signature.

ALBERT DELAS. 

